Power supply apparatus



Nov. 15, 1949 A. G. OWEN POWER SUPPLY APPARATUS Filed Feb. 8, 1947 IN VEN TOR. A/enf G Owen BY ffanney Patented Nov. 15, 1949 POWER SUPPLY APPARATUS Albert G. Owen, Sharon, Mass, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 8, 1947, Serial No. 727,439

6 Claims. (Cl. 321-25) This invention relates to apparatus for the production of relatively high voltage, direct current from relatively low voltage, alternating current, and relates more particularly to automatic controls for such apparatus.

For energizing electric units such, for example, as electrostatic precipitators which require relatively high voltage, direct current, from relatively low voltage, alternating current lines, it is customary to provide power supply apparatus using step-up transformers and rectiflers. This invention provides for such apparatus, automatic voltage regulation; the prevention of a shortcircuit across its output; and the indications of an open load circuit, and of a short-circuited load circuit.

An object of the invention is to regulate the voltage of the current delivered by power supply apparatus.

Another object of the invention is to prevent a short-circuit across the output of power supply apparatus.

Other objects of the invention are to indicate open and short-circuits in the load connected to power supply apparatus.

The invention will now be described with reference to the drawing which is a circuit schematic illustrating one embodiment of this invention.

The embodiment of the invention illustrated comprises the step-up transformer 5 which is adapted to have its primary winding 6 connected to the 117 volt, alternating current wires 4. One side of the secondary winding 1 of the transformer is connected to the anode 8 of the halfwave rectifier tube 9. The cathode I0 is connected to the high voltage, direct current terminal The other side of the secondary winding 1 is connected to one side of the winding 2 of the saturable reactor l3, the other side of the winding l2 being connected to the intermediate voltage, direct current terminal I4.

The secondary winding 1 is tapped at l5, the

tap being connected to the cathode l6 of the half-wave rectifier tube H. The anode l8 of the tube I1 is connected to one end of the resistor IS, the other end of the resistor being connected to the minus terminal 20. The condenser 2| is connected between the terminals II and I4, and the condenser 22 is connected between the terminals l4 and 20.

The filament cathodes of the tubes 3 and i1 could be energized by current from a filament winding which is not illustrated, of the transformer 5, or from a separate filament transformer.

The circuit described in the foregoing is a more or less conventional, full wave, voltage multiplier circuit, the tube 9 rectifying the alternating current during one half-cycle, at which time the condenser 2| charges up to the peak of the direct current voltage. The tube l'l rectifies the alternating current during the next half-cycle, at which time the condenser 22 charges up to the peak of the direct current voltage from the tube IT. The condenser 2| discharges during the half-cycles the tube I1 is rectifying, and its output is delivered in series with that from the tube l'l. Likewise the condenser 22 discharges during the half-cycles the tube 9 is rectifying, and its output is delivered in series with that from the tube 9. I Thus the terminal may supply +13,000 volts to a load, and the terminal l4 may supply +6,000 volts to the load, the negative side of the load being connected to the terminal 20.

As the current drawn by the load increases, the delivered voltage ordinarily would decrease. This invention provides a saturable reactor for maintaining the load current, and therefore the delivered voltage, constant. The saturable reac tor becomes a load when a short-circuit occurs in the normal load, thus preventing a short-circuit across the output of the power supply.

The rectifier tube 5| and the dual-triode tube 54 have their filaments 23 and 24 respectively, connected in series with the voltage dropping resistor 25, to the 117 volt alternating current wires 4. The tube 5| may be a 50Z7, the tube 54 may be a 12SL7, and the resistor 25 may be 350 ohms. The anodes 26 of the rectifier tube 5| are corinected together and to one of the wires 4. The cathodes 21 of the tube 5| are connected together and to one side of the winding 28 of the relay 29, the other side of the winding 28 being connected to one side of the winding 30 of. the saturable reactor I3. The other'side of the winding 30 is connected by the wire 3| to the anode 32 of the tube 54.

The cathodes 21 of the rectifier tube 5| are also connected to one side of the winding 33 of the relay 34, the other side of the winding 33 being connected to the anode 35 of the tube 54.

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armature 30 o! the relay 2! is connected oi the supply wires 4, and the contact Il relay II is connected to one of the elecoi' the neon tube 33, the other, electrode of the tube 3| being connected to the other of the supply wires 4. when the relay 29 releases its armature 35, a circuit is closed for lighting the tube 33 with current irom the supply wires 4.

The armature 40 the relay 34 is connected to one oi the wires 4. The contact 4| of the relay 34 is connected to one of the electrodes oi the neon tube 4!, its other electrode being connected to the other of the supply wires 4. The armature 43 touches the contact 4| and closes a circuit lighting the lamp 4! with current from the supply wires l when the relay 34 is energized.

The tap 45 on the resistor is is connected to the control grid 44 of the tube 54, and to one end of the bias resistor 48, the other end or which is connected to the cathode 41 of the tube 54.

The slider 43 of the resistor i9 is connected to one of the supply wires 4 and to one end of the cathode bias resistor 43, the other end of which is connected to the cathode 43 of the tube 54.

The slider 50 Of the resistor I9 is connected to the control grid ti 0! the tube 54.

The rectifier tube supplies direct current to energize the tube 54 and the relays 29 and 34. The condenser 52 filters the output of the tube 5 i.

In operation, the current drawn by the load connected to the terminals II, N and 20 flows through the resistor is causing proportional voltage drops through the resistor. An increase in current to a value above normal for the load causes an increased voltage drop across the resistor, and causes an increase in the voltage between the grid 44 and the cathode 49 of the tube 54, the grid being negative and the voltage increase being an increase in the negative voltage on the grid. This causes a decrease in the current flowing from the anode 32 of the tube, through the winding 30 oi the saturable reactor i3. This causes an increase in the impedance of the winding I! of the reactor which in turn causes the load current to decrease to the normal value. Likewise a decrease in current to a value below normal for the load, causes a decreased voltage drop across the resistor I9, and causes a decrease in the voltage between the grid 44 and the cathode 43 oi the tube 54. This causes an increase in the current flowing from the anode 32 of the tube through the winding 30 of the reactor l3, and causes a decrease in the impedance of the winding l2, resulting in an increase in the load current to the normal value. The slider 43 is adjustable to cause any selected current to be maintained constant. Through holding the current constant the voltage of the current is also held constant.

In case of a short-circuit in the load connected to the power supply, the increase in current caused thereby does two things. First it results in the grid 44 or the tube 54 being biased with so high a negative voltage that substantially no current will fiow through the winding 30 of the reactor II. This greatly increases the impedance o! the winding I! of the reactor causing the reactor to act as a sufiicient load for greatly limiting current value. At the same time the decrease in the current from the anode 32 of the tube 54, which current flows through the relay winding 23, decreases to so low a value that the relay armature 38 is released causing it to touch the contact 31, and thereby cause the Neon lamp 33 which may be colored red, to light, indicating said relay so as to be actuated thereby when abto an attendant that there is a short-circuit in the load.

In case an open circuit occurs, the current through the resistor It will decrease to zero resulting in no negative bias on the grid SI of the tube 54, causing the tube to draw so much space current that the current flowing from its anode 35 through the relay winding 33, energizes the relay 34 causing it to pull-up its armature 40 which then touches the contact 4i causing the Neon lamp 42 which may be colored green, to light, indicating to an attendant that there is an open circuit.

The embodiment of the invention illustrated is particularly suitable for energizng electrostatic precipitators having ionizer electrodes, and separate collector electrodes such as disclosed in the G. W. Penny Patent No. 2,129,783. The ionizer electrodes would be connected to the terminals l l and 20, which would provide a potential of 13,000 volts, for example, therebetween. One set oi collector electrodes would be connected to the terminal l4 and the other to the terminal 20, which would provide a potential of 6,000 volts, for example, therebetween.

The winding 12 of the saturable reactor I3 is placed in the lead between the tapped connection on the transformer secondary winding and the intermediate voltage terminal, in which lead alternating current flows, and due to this location, but one such reactor is required for adequate voltage regulation. Thus th s invention is particularly suitable ior voltage multiplier circuits.

While one embodiment of the invention has been described for the purpose of illustration, it should be understood that the invention is not limited to the exact circuit and circuit components illustrated, as modifications thereof may be suggested by those skilled in the art without departure from the essence of the invention.

What is claimed is:

1. Power supply apparatus comprising a voltage step-up transformer having a secondary winding, 9. pair of rectifier elements each having a cathode and an anode, a. pair of load supply leads, one connected to the cathode of one of said devices, the other connected to the anode of the other of said devices, a pair of condensers connected in series and to said leads, a saturable reactor having first and second coils, said winding being connected at one end to the anode of said one of said devices and at the other end to one end of said first coil, an intermediate point on said winding being connected to the cathode of the other of said devices, the other end of said first coil being connected to the mid-point connection of said condensers, a resistor connected in one of said leads, a vacuum tube having a control grid, a cathode and an anode, a source of direct current for supplying space current for said tube, said anode of said tube being connected to one end of said second coil, the other end of said second coil being connected to said source, and means connecting said grid and the cathode of said tube to said resistor whereby voltage variations thereacross vary the voltage between said grid and said cathode and vary the current flowing from said source through said second coil.

2. Power supply apparatus as claimed in claim 1 in which a relay has its energizing winding connected in series with said second coil and said source, and a signalling device is connected to normal current flows through said energizing winding.

3. Power supply apparatus as claimed in claim 1 in which an open-circuit signal device and a short-circuit signal device are provided, means including means actuated when no current is flowing through said resistor is provided for actuating said open-circuit device, and means including means responsive to an abnormally large current flowing through said resistor is provided for actuating said short-circuit device.

4. Power supply apparatus comprising a voltage step-up transformer having a secondary winding; a pair of rectifier elements each having a cathode and an anode; one element having its anode connected to said winding at one end thereof and having its cathode connected to a high potential, load supply lead; the other of said elements having its cathode connected to a tap on said winding, and having its anode connected to the negative, load supply lead; a saturable reactor having one winding connected atone end to said winding at the other end thereof, the reactor having the other end of Said one winding conected to an intermediate potential, load supply lead; said reactor having a second winding inductively coupled to its other winding; means including means responsive to current flowing through one of said leads for supplying current to said second winding which is inversely proportional to said current; a relay having an energizing winding connected to said second winding so as to have current flowing therethrough which varies with the current flowing through the second winding, and a signal device actuated bysaid relay when a relatively high current flows through its energizing winding.

5. Power supply apparatus as claimed in claim is a resistor connected in the negative lead.

6. Power supply apparatus comprising a voltage step-up transformer having a, secondary winding; 9. pair of rectifier elements, each having a cathode and an anode; a pair of load supply leads; one connected to the cathode of one of said devices, the other connected to the anode of the otherof said devices, a pair of capacitors connected in series and to said leads; a saturable reactor having first and second coils; said winding being connected at one end to the anode of said one of said devices, and. at the other end to one end of said first coil, the other end of said first coil being connected to the mid-point connection of said capacitors, means including means responsive to current flowing in one of said supply leads for supplying current to said second coil which varies inversely with said current; a relay having an energizing winding connected to said second coil so as to have current flowing therethrough which varies with the current flowing through said second coil, and a signal device operated by said relay when an abnormal current flows through its energizing winds- V ALBERT G. OWEN.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 1,902,227 Garretson Mar. 21, 1933 2,018,348 Dijksterhuis Oct. 22, 1935 2,036,708 Logan Apr. 7, 1936 I 2,213,091 Morack Aug. 27, 1940 2,309,156 Andrews Jan. 26, 1943 OTHER REFERENCES Shade-R. I". High Volt Supplies, pub. April 1943, No.8t235 by R. C. A page 161. 

